Pump assembly



Sept. 6, 1966 SAND ET AL 3,270,679

PUMP ASSEMBLY Filed Aug. 13, 1964 v mvzzlwoR. flax-rel 1? Sand 5 By (7/1210 272 Cozmd/ ATTORNEY United States Patent 0 3,270,679 PUMP ASSEMBLY Darrel R. Sand, Plymouth, and Arlan M. Connell,

Livonia, Mich., assignors to General Motors Corporation, Detroit, Mich, a corporation of Delaware Filed Aug. 13, 1964, Ser. No. 389,256 8 Claims. (Cl. 103126) This invention relates to pumps, and particularly to pumps of the type commonly used in automatic transmissions for automotive vehicles for supply of transmission control and lubrication pressures.

It is common practice to use pumps of the internal external type wherein a pair of rotary members are provided with spaced teeth which rotate in mesh with each other. In such pumps, a partition is disposed between an intake and a delivery chamber and the pump teeth of each rotary member contact the partition. The teeth and partition form fluid carrying pockets which deliver fiuid from the low pressure intake chamber to the high pressure delivery chamber. Such pumps have the disadvantage that it is diflicult to effect and maintain sealing contact between the moving teeth and the partition. It is comrnon practice to form the partition integrally with the pump housing and in such constructions, the variation in individual pumps arising from manufacturing tolerances results in pumps having a wide range of pump capacity such that pumps of a given design are not uniform in their ability to produce pressure or fluid flow.

In the patent to Hardy 2,875,700 there is disclosed an improved construction wherein the partition is formed of spring material and is permitted to float or move slightly with respect to the housing. While the Hardy construction represents an improvement over the standard construction, it has been found that there is fluid leakage through the spring partition due to the fact that the partition may at times assume an undesirable angle with respect to the gear teeth. The present invention provides an improved floating partition and an improved anchoring means for anchoring the partition to the pump housmg.

In quantity production of pumps of the type described, there are slight but unavoidable variations in the diameter of the circles forming the ends of the gear teeth, variations in eccentricity of mounting the gears, variations in forming and locating the surfaces of the crescent partition, and other manufacturing tolerances which result in poor fit between the crescent partition and the teeth of one gear or both. This results in internal pump leakage, reduces the pressure the pump is designed to maintain. In addition, normal wear reduces the pump efficiency.

It is an object of this invention to provide an improved pump incorporating an improved floating partition for preventing internal pump leakage normally arising from manufacturing tolerances and from wear due to use.

An additional object of this invention is to provide a pump having a partition formed of strip material and having spaced contact surfaces adapted to contact pump teeth wherein a resilient member disposed in the space between the contact surfaces biases the contact surfaces of the partition into contact with the pump teeth.

A further object of this invention is to provide a pump of the type described wherein the resilient member is anchored to the pump housing and provides the sole support for the partition contact member in the installed Patented Sept. 6, 1966 static condition and in the average normal pressure position to permit limited movement of the partition contact member relative to the pump teeth.

Another object of this invention is to provide a pump of the type described wherein a resilient member is normally effective to bias a partition contact member into contact wtih the pump teeth and wherein the opposite ends of the resilient member are seated upon support members connected to the pump housing.

A specific object of this invention is to provide a pump of the type described wherein a crescent spring is supported upon spaced anchor pins through a resilient spring insert wherein the insert provides for noise dampening and also seals the pressurized fluid from leakage to the pump suction chamber along the sides of the pump.

Another object of this invention is to provide a pump of the type described wherein one of the crescent spring anchor pins is located in the high pressure zone to prevent the crescent from being jammed into the gear teeth at high line pressures and a second anchor pin is located in the low pressure zone and holds the crescent in place against the frictional drag of the rotating teeth at low line pressures.

An additional object of the invention is to locate the anchor pins as described to allow free assembly of the spring under all tolerance conditions.

A further object of this invention is to provide in a pump as described, a flexible support for the spring provided with a pair of spaced slots or openings therein to allow the flexible support to be squeezed or partially compressed to facilitate assembly and allowing positive contact with the spring without excessively loading the spring against the gear teeth.

Another object of this invention is to provide a pump having spaced support pins abutting the opposite ends of a generally arcuate shaped flexible support member, to provide a spring strip gear tooth contact member having spaced arcuate shaped gear tooth contact surface supported on the flexible support member for limited motion relative to the pump gear teeth wherein the resilient support member substantially fills the space between the gear tooth contact surfaces of the contact member and wherein the pressure in the pump pressure chamber is effective upon one end of the flexible support member to cause the flexible support member to expand transversely of the plane of rotation of the pump gears into contact with the side walls of the pump housing to minimize leakage of fluid past the side walls of the flexible support member.

These and other objects and advantages of this invention will be apparent from the following specification and claims taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a cross section, partly diagrammatic, of a pump embodying the invention.

FIGURE 2 is a section on the line 22 of FIGURE 1.

FIGURE 3 is a side view of a resilient spring in its expanded position.

FIGURE 4 is a side view of the flexible spring support member.

Referring to FIGURE 1, there is shown an improved pump constructed in accordance with the principles of this invention. The pump indicated generally at 5 includes an annular or internal gear 10 having teeth 11 extending internally from its body and an external gear 12 having teeth 13 extending externally from its body.

Gear 12 is disposed eccentrically with respect to gear so that the gears define a generally crescent-shaped pumping chamber 14 therebetween. Gear 12 is keyed to a drive shaft 16 for rotation therewith and in a counterclockwise direction as indicated by the arrow. The gears are mounted in a circular chamber 18 formed by pump housing 6. Housing 6 thus provides a circular bearing for the external surface 19 of internal gear 10.

A composite partition indicated generally at 20 is positioned in pumping chamber 14, to separate a suction chamber 42 from a pressure delivery or high pressure chamber 43. A pair of spaced studs 21, 22 carried by housing 6 extend transversely of the space between the internal and external gear teeth 11 and 12.

Partition 20 is of composite structure including a thin flexible elastic strip 23 formed of spring steel and bent into the shape shown in FIGURE 3. When so formed, strip 23 embodies one arcuate base contact portion 24 adapted to fit the ends of external teeth 13 of gear 12 and a pair of spaced arms or contact portions 25 and 26 adapted to fit the internal teeth 11 of gear 10. Members 25 and 26 have their free ends bent inwardly at 27 and 28 to provide a gradual engagement and disengagement with teeth 11 of gear 10.

As best shown in FIGURE 4, a flexible moulded generally crescent-shaped insert indicated generally at 30, preferably formed of rubber, is provided with a surface 31 conforming to the shape of arcuate member 24 of spring 23 and a pair of spaced surfaces 33 and 34 conforming to the shape of spring contact surfaces 25 and 26. A recess 32 between surfaces 33 and 34 receives the bent-in ends or spring fingers 27 and 28 and acts as a clearance for the spring ends 27 and 28. As shown in FIGURE 1, the opposite ends of insert 30 are provided with recesses 35 and 36 which conform to the diameter of pins 21 and 22.

In assembling the partition 20 into the pump, the spring contact member 23 is first assembled such that the pins 21 and 22 are disposed within the contact member 20 and spaced from the bent-end portions 38 and 39 by which contact surface 24 is joined to contact arms 25 and 26. Rubber insert 30 is then slid into member 23 such that the pins 21 and 22 seat in recesses 36 and 35, and the bent ends 27, 28 of contact arms 25 and 26 extend into groove 32. When assembled, insert 30 provides the sole support for spring 23. Member 30 thereby provides a flexible support for the spring 23 whereby spring 23 may move slightly relative to the gear teeth in order to provide good tooth contact between the contact surfaces of the spring and the teeth to reduce internal leakage in the pump. In addition, rubber insert 30 biases the contact surfaces 24, 25 and 26 outwardly into contact with the gear teeth to further reduce internal pump leakage. Otherwise stated, insert 30 is under slight compression when inserted into member 20 to urge the spring into contact with the gear teeth of both gears. This slight pressure will assure good contact of the spring and teeth irrespective of variations in tooth length due to manufacturing tolerances or wear. The resilient floating mount of the spring will permit the spring to maintain proper gear teeth contact in spite of improper eccentricity which may arise due to manufacturing tolerances and wear. The partition is inexpensive to manufacture and assemble since the contact arms 25 and 26 automatically grip the rubber insert when in assembled relationship with the insert.

As shown in FIGURE 1, a pump inlet chamber 42 may be connected to a fluid source through a port 41 and a passage 40. High pressure chamber 43 may deliver fluid under pressure through a port 44 and a passage 45.

With the present mounting arrangement, the pump may be driven either clockwise or counterclockwise as desired without any change in the partition. The partition will readily accommodate itself for pump rotation in either direction. Assuming counterclockwise rotation, pin 22 in the high pressure portion of the pump will prevent the leading end of contact surface 25 of spring 23 from being jammed into the gears at high line or pressure delivery pressures. The clearance space between walls 25 and 24 in the zone of bend 39 and pin 22 is selected such that pin 22 will contact the wall of base 24 to prevent any jamming of the spring member into the gear teeth. Pin 21, on the other hand, holds the spring in place against the action of frictional drag of the rotating teeth at low line pressures. Thus, while rubber insert 30 in cooperation with pins 21 and 22 permits limited deflection of spring 20 relative to the gear teeth, the pins also may contact the opposite ends of members 23 to limit the permissible range of deflection of the spring relative to the gear teeth. A pair of spaced slots 46 and 47 extend through rubber insert member 30 to allow the insert to be squeezed into position in the assembly. The slots also reduce the effective outward thrust of insert 30 upon the surfaces 24, 25 and 26 of spring 23 so that these surfaces are not excessively loaded into contact with gear teeth 11 and 13.

As shown in FIGURE 2, rubber insert 30 is coextensive in width with the width of spring 23 and these members contact the side walls 48 and 49 of the pump housing pump chamber to minimize fluid leakage from the high pressure chamber to the suction side of the pump. Insert 30 also reduces fluid leakage through the gap between surfaces 24, 25 and 26 of spring 23 in that it fills the space and surfaces 33 and 34 contact arms 25 and 26 and surface 31 contacts portion 24. When assembled the surfaces 33, 34 and 31 conform to the shape of arms 25, 26, and surface 24 and due to the compression of member 30 when assembled, the pressure exerted by member 30 prevents leakage of fluid both externally between the gear teeth and the spring and internally between the spring and member 30.

The floating adjustment of the contact surfaces relative to the gear teeth afforded by the resilient member 30 assures proper tooth contact irrespective of wear or manufacturing tolerances. At the same time, pins 21 and 22 cooperate with the contact member 23 to limit the permissible range of motion of contact member 23 arising from the effect of pressure in pressure chamber 43 and drag due to contact with the gear teeth.

Further additional improved sealing against internal fluid leakage from pressure chamber 43 to suction chamber 41 is accomplished by the deformation of resilient support member 30 against the side walls 48 and 49 of the pump housing (see FIGURE 2) caused by the pressurized oil in chamber 43 acting against the surface or end 35 of flexible support 30. It will be apparent that the improved structure readily accommodates itself to variations in manufacturing tolerances and wear to minimize internal leakage through the pump over a long range of useful life and is of inexpensive construction and adapted for rapid and inexpensive assembly in large scale production.

What is claimed is:

1. A pump comprising in combination a housing, an external gear meshing with .an internal gear and located eccentrically Within said internal gear to provide a generally crescent-shaped space between said gears, said housing enclosing said gears and defining with said gears a pumping space, a pair of spaced support members extending transversely of said pumping space, a resilient support member seated on aid spaced support members, respectively, a partition carried by said resilient support member dividing said pumping space into intake and pressure delivery chambers, said resilient support member and said partition extending transverse of said pumping space and being in contact with said housing, said partition also being in contact with the ends of the teeth of both gears and having curved extremities for providing contact surfaces with said spaced support members, respectively.

2. A pump comprising in combination an internal gear, an external gear meshing with said internal gear and positioned eccentrically within the internal gear to provide a generally crescent-shaped space between said gears, means having surfaces enclosing said gears and defining with said gears a pumping space, a composite partition separating said space into an intake chamber and a pressure delivery chamber, said composite partition including a resilient member and a contact member supported upon said resilient member, a pair of spaced support members extending transversely of said pumping space for supporting said resilient member in said space, said resilient member being disposed within said contact member for supporting the same and for urging said contact member into contact with said external and internal gears, the extremities of said contact member being curved to provide cooperating contact surfaces with said spaced support members, respectively.

3. A pump comprising in combination an internal gear, an external gear meshing with said internal gear and located eccentrically within the internal gear to provide a generally crescent-shaped space between said gears, housing means having surfaces enclosing said gears and defining with said gears a pumping space, a composite partition separating said space into an intake chamber and a pressure delivery chamber, said partition including a contact member having spaced arcuate-shaped portions adapted to contact said external and internal gears respectively, a pair of spaced rigid support members extending transversely of said space, and a resilient support member disposed within said contact member and urging said contact member into contact with said internal and external gears, said rigid support members being in contact engagement with the opposite ends of said resilient support member, said spaced arouate shaped portions being joined together by a curved portion at each extremity of said contact member, said curved portions providing contact surfaces cooperating with said rigid support members, respectively.

4. A pump comprising in combination an internal gear, an external gear meshing with said internal gear and positioned eccentrically within said internal gear to provide a generally crescent-shaped space between said gears, a pump housing having a pair of surfaces enclosing said gears and defining with said gears a pumping space, a composite partition dividing said space into intake and pressure delivery chambers, said composite partition including a first member extending between and being in contact with said surfaces and extending between and being in contact with the ends of the teeth of both of said gears, said composite partition also including a resilient member disposed within said first member and contacting said surfaces and effective to bias said first member into contact with the teeth of both of said gears, and a pair of spaced anchor pins abutting said resilient member for connecting said resilient member to said housing, said first member of said composite partition having curved portions at its extremities providing contact surfaces cooperating with said anchor pins, respectively.

5. A pump comprising in combination an internal gear, an external gear meshing with said internal gear and positioned eccentrically within said internal gear to provide a generally crescent-shaped space between the gears, housing means having surfaces enclosing said gear and defining with said gears a pumping space, a composite partition dividing said space into an intake chamber and a pressure delivery chamber, said partition including a contact member and a resilient support member, said contact member including an arcuate-shaped base portion substantially fitting said external gear and a pair of contact arms for contacting said internal gear, said arms being formed integrally with said base portion and being joined to said base portion by curved connections at the opposite extremities of said base portion, a. pair of spaced rigid support members extending transversely of said pumping space, each of said rigid support members extending between said base portion and one of said arms of said contact member, said curved connections providing contact surfaces cooperating with said spaced rigid support members, respectively, aid resilient member being disposed in the space between said base portion and said arms of said contact member and in abutting relationship with said spaced rigid support members, said resilient support member biasing said base portion and said arms of said contact member into contact relationship with the teeth of said external gear and said internal gear, respectively.

6. A pump comprising in combination an internal gear, an external gear meshing with said internal gear and positioned eccentrically within said internal gear to provide a generally crescent-shaped space between said gears, a housing having surfaces enclosing said gears and defining with said gears .a pumping space, a composite partition dividing said pumping space into an intake chamber and a delivery chamber, said partition including a contact member for contacting the teeth of said internal and external gears and a resilient support member for urging said contact member into contact with said gear teeth, said support member being disposed within said contact member, said contact member and said resilient support member extending transversely of said pumping space to contact said housing surfaces, 21 pair of spaced support members extending transversely of said chambers and abutting the opposite ends, respectively, of said resilient member, said resilient member permitting limited motion of said contact member relative to said gear teeth, said contact member having curved extremities providing contact surfaces cooperating with said spaced support members, respectively.

7. A pump comprising in combination an internal gear, an external gear meshing with said internal gear and positioned eccentrically within said internal gear to provide a generally crescent-shaped space between said gears, a housing having surfaces enclosing said gears and defining with said gears a pumping space, a composite partition dividing said pumping space into an intake chamber and a pressure chamber, said partition including a contact member having a base portion for contacting the teeth of said external gear and a pair of arms bent up from said base portion and spaced from said base portion for contacting the teeth of said internal gear, said partition also including a resilient support member disposed within said contact member for urging said base portion and said arms into contact with said gear teeth, first and secand ground members extending transversely of said pumping space and disposed in said pressure chamber and said intake chamber, respectively, said resilient mem her being engaged by aid ground members, said ground members extending between said base and said arms of said contact member and adapted to contact said contact member to limit the permissible deflection of said contact member relative to said gear teeth.

8. A pump comprising a housing having spaced side Walls enclosing a chamber, an external gear meshing with an internal gear and positioned eccentrically within said internal gear to provide a generally crescent-shaped space between said gears, said housing and side walls enclosing said gears, a pumping space, first and second fixed support members fixed to said housing and extending transversely of said pumping space, a resilient support member disposed in said pumping space and having first and second ends supported upon said first and second fixed support members, respectively, said resilient support member extending transversely of said pumping space into contact with spaced side walls of said housing, a gear tooth contact member supported upon said resilient member and having surf-ace contacting said external and internal gears, respectively, said resilient support member 7 8 and gear tooth contact member dividing said pumping References Cited by the Examiner space into spaced high pressure and suctions chambers, UNITED STATES PATENTS respectively, said pressure in said high pressure chamber 2 432 713 9 1949 Jones 103 12 being effective upon said first end of said resilient sup- 5 2,875,700 3/1959 Hardy 103-426 port member to expand said resilient support member 2,933,046 4/1960 McCray 7 into contact with said spaced housing side walls to prevent f 'i i s g g? fluid leakage from said high pressure chamber to said low pressure chamber said gear tooth contact member MARK NEWMAN, Primary Examinerhaving curved extremities providing Contact surfaces com SAMUEL LEVINE, Examiner. operating with said fixed support members, respectively. L FREEH Assistant Examiner. 

1. A PUMP COMPRISING IN COMBINATION A HOUSING, AN EXTERNAL GEAR MESHING WITH AN INTERNAL GEAR AND LOCATED ECCENTRICALLY WITHIN SAID INTERNAL GEAR TO PROVIDE A GENERALLY CRESCENT-SHAPED SPACE BETWEEN SAID GEARS, SAID HOUSING ENCLOSING SAID GEARS AND DEFINING WITH SAID GEARS A PUMPING SPACE, A PAIR OF SPACED SUPPORT MEMBERS EXTENDING TRANSVERSELY OF SAID PUMPING SPACE, A RESILIENT SUPPORT MEMBER SEATED ON SAID SPACED SUPPORT MEMBERS, RESPECTIVELY, A PARTITION CARRIED BY SAID RESILIENT SUPPORT MEMBER DIVIDING SAID PUMPING SPACE INTO INTAKE AND PRESSURE DELIVERY CHAMBERS, SAID RESILIENT SUPPORT MEMBER AND SAID PARTITION EXTENDING TRANSVERSE OF SAID PUMPING SPACE AND BEING IN CONTACT WITH SAID HOUSING, SAID PARTITION ALSO BEING IN CONTACT WITH THE ENDS OF THE TEETH OF BOTH GEARS AND HAVING CURVED EXTREMITIES FOR PROVIDING CONTACT SURFACES WITH SAID SPACED SUPPORT MEMBERS, RESPECTIVELY. 